The Dockerfile missed some fixtures, which caused this test
fail when running from this image.

I also noticed some other fixtures missing in integration-cli,
where the image had symlinks to some certificates, but the
original files were not included;

```
|-- integration-cli
|-- fixtures
| |-- auth
| | `-- docker-credential-shell-test
| |-- credentialspecs
| | `-- valid.json
| |-- https
| | |-- ca.pem -> ../../../integration/testdata/https/ca.pem
| | |-- client-cert.pem -> ../../../integration/testdata/https/client-cert.pem
| | |-- client-key.pem -> ../../../integration/testdata/https/client-key.pem
| | |-- client-rogue-cert.pem
| | |-- client-rogue-key.pem
| | |-- server-cert.pem -> ../../../integration/testdata/https/server-cert.pem
| | |-- server-key.pem -> ../../../integration/testdata/https/server-key.pem
| | |-- server-rogue-cert.pem
| | `-- server-rogue-key.pem
```

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 48fd0e921c53c1c195dad1e33e6be3bac4ec5cbd)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>